Although quality assurance and quality control procedures are routinely applied in most air quality networks, outliers can still occur due to instrument malfunctions, the influence of harsh environments and the limita...Although quality assurance and quality control procedures are routinely applied in most air quality networks, outliers can still occur due to instrument malfunctions, the influence of harsh environments and the limitation of measuring methods. Such outliers pose challenges for data-powered applications such as data assimilation, statistical analysis of pollution characteristics and ensemble forecasting. Here, a fully automatic outlier detection method was developed based on the probability of residuals, which are the discrepancies between the observed and the estimated concentration values. The estimation can be conducted using filtering—or regressions when appropriate—to discriminate four types of outliers characterized by temporal and spatial inconsistency, instrument-induced low variances, periodic calibration exceptions, and less PM_(10) than PM_(2.5) in concentration observations, respectively. This probabilistic method was applied to detect all four types of outliers in hourly surface measurements of six pollutants(PM_(2.5), PM_(10),SO_2,NO_2,CO and O_3) from 1436 stations of the China National Environmental Monitoring Network during 2014-16. Among the measurements, 0.65%-5.68% are marked as outliers. with PM_(10) and CO more prone to outliers. Our method successfully identifies a trend of decreasing outliers from 2014 to 2016,which corresponds to known improvements in the quality assurance and quality control procedures of the China National Environmental Monitoring Network. The outliers can have a significant impact on the annual mean concentrations of PM_(2.5),with differences exceeding 10 μg m^(-3) at 66 sites.展开更多
Air pollution induces significant health risks to individuals exposed to high levels of pollutants concentration. For ground vehicles, pollutants infiltrate the car cabin through the ventilation system, leading to pot...Air pollution induces significant health risks to individuals exposed to high levels of pollutants concentration. For ground vehicles, pollutants infiltrate the car cabin through the ventilation system, leading to potential health issues. To address this problem, a project was undertaken to develop a protocol for characterizing in-cabin air quality. The study involved a closed chamber (the bubble) where its internal multiphase flow has been optimized to create controlled polluted atmospheres. Experiments were conducted to optimize the positioning of the stirring fan and particle generation source, ensuring a homogeneous distribution of fine and ultrafine particles. This study demonstrated the feasibility of implementing a platform dedicated to characterizing the vehicles’ in-cabin air quality under controlled conditions. It allows a better understanding of the dynamics of particle infiltration and the establishment of an optimized protocol for simultaneous measurements of indoor and outdoor concentrations.展开更多
In studying indoor atmospheric pollution,the concentration of air pollutants is considered to be the primary factor in judging indoor pollution level,while sensory effects accessed by olfactory analysis has not been p...In studying indoor atmospheric pollution,the concentration of air pollutants is considered to be the primary factor in judging indoor pollution level,while sensory effects accessed by olfactory analysis has not been paid enough attention.In this paper,twenty living rooms in Beijing including newly decorated,3 months and 6 months after decoration were sampled once a day for 10 d,and qualitative analysis,quantitative analysis and olfactory analysis of volatile organic compounds were carried out.The results showed the concentrations of the 6 main compounds surpassed the limitation values released by World Health Organization;the pollutants with highest chemical concentrations were not the most odor active odorants.Olfactory analysis which measured the odor characters such as odor detection threshold(ODT),odor active value(OAV) and odor quality was a helpful tool to identify possible chemicals which cause indoor smelling issues,and it was necessary to access indoor air quality in combination with their chemical concentrations to give a comprehensive judgment on indoor air quality.展开更多
基金supported by the National Natural Science Foundation (Grant Nos.91644216 and 41575128)the CAS Information Technology Program (Grant No.XXH13506-302)Guangdong Provincial Science and Technology Development Special Fund (No.2017B020216007)
文摘Although quality assurance and quality control procedures are routinely applied in most air quality networks, outliers can still occur due to instrument malfunctions, the influence of harsh environments and the limitation of measuring methods. Such outliers pose challenges for data-powered applications such as data assimilation, statistical analysis of pollution characteristics and ensemble forecasting. Here, a fully automatic outlier detection method was developed based on the probability of residuals, which are the discrepancies between the observed and the estimated concentration values. The estimation can be conducted using filtering—or regressions when appropriate—to discriminate four types of outliers characterized by temporal and spatial inconsistency, instrument-induced low variances, periodic calibration exceptions, and less PM_(10) than PM_(2.5) in concentration observations, respectively. This probabilistic method was applied to detect all four types of outliers in hourly surface measurements of six pollutants(PM_(2.5), PM_(10),SO_2,NO_2,CO and O_3) from 1436 stations of the China National Environmental Monitoring Network during 2014-16. Among the measurements, 0.65%-5.68% are marked as outliers. with PM_(10) and CO more prone to outliers. Our method successfully identifies a trend of decreasing outliers from 2014 to 2016,which corresponds to known improvements in the quality assurance and quality control procedures of the China National Environmental Monitoring Network. The outliers can have a significant impact on the annual mean concentrations of PM_(2.5),with differences exceeding 10 μg m^(-3) at 66 sites.
文摘Air pollution induces significant health risks to individuals exposed to high levels of pollutants concentration. For ground vehicles, pollutants infiltrate the car cabin through the ventilation system, leading to potential health issues. To address this problem, a project was undertaken to develop a protocol for characterizing in-cabin air quality. The study involved a closed chamber (the bubble) where its internal multiphase flow has been optimized to create controlled polluted atmospheres. Experiments were conducted to optimize the positioning of the stirring fan and particle generation source, ensuring a homogeneous distribution of fine and ultrafine particles. This study demonstrated the feasibility of implementing a platform dedicated to characterizing the vehicles’ in-cabin air quality under controlled conditions. It allows a better understanding of the dynamics of particle infiltration and the establishment of an optimized protocol for simultaneous measurements of indoor and outdoor concentrations.
基金supported by the National High Technology Research and Development Program of China(2012AA030302)the National Natural Science foundation of China(20877008,21277011)+1 种基金the Program for New Century Excellent Talents in University(NCET-09-0218)the Fundamental Research Funds for the Central Universities(FRF-TP-10-004B, FRF-BR-11-017B)
文摘In studying indoor atmospheric pollution,the concentration of air pollutants is considered to be the primary factor in judging indoor pollution level,while sensory effects accessed by olfactory analysis has not been paid enough attention.In this paper,twenty living rooms in Beijing including newly decorated,3 months and 6 months after decoration were sampled once a day for 10 d,and qualitative analysis,quantitative analysis and olfactory analysis of volatile organic compounds were carried out.The results showed the concentrations of the 6 main compounds surpassed the limitation values released by World Health Organization;the pollutants with highest chemical concentrations were not the most odor active odorants.Olfactory analysis which measured the odor characters such as odor detection threshold(ODT),odor active value(OAV) and odor quality was a helpful tool to identify possible chemicals which cause indoor smelling issues,and it was necessary to access indoor air quality in combination with their chemical concentrations to give a comprehensive judgment on indoor air quality.
